• Source: Ring spectrum
    • In stable homotopy theory, a ring spectrum is a spectrum E together with a multiplication map

      μ: E ∧ E → E
      and a unit map

      η: S → E,
      where S is the sphere spectrum. These maps have to satisfy associativity and unitality conditions up to homotopy, much in the same way as the multiplication of a ring is associative and unital. That is,

      μ (id ∧ μ) ~ μ (μ ∧ id)
      and

      μ (id ∧ η) ~ id ~ μ(η ∧ id).
      Examples of ring spectra include singular homology with coefficients in a ring, complex cobordism, K-theory, and Morava K-theory.


      See also


      Highly structured ring spectrum


      References



      Adams, J. Frank (1974), Stable homotopy and generalised homology, Chicago Lectures in Mathematics, University of Chicago Press, ISBN 0-226-00523-2, MR 0402720

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